Safety-valve.



R. GOGKBURN & 1). MAQNIGOLL. SAFETY VALVE.

APPLICATION FILED JULYVIB, 1912.

Patented Mar. 18, 1913.

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R. GOGKBURN 61: D. MAuNlGOLL.

SAFETY VALVE.

APPLICATION FILED JULY 13, 1912.

Patented Mar. 18, 1913.

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SAFETY-VALVE.

Specification of Letters Patent.

Application filed July 13, 1912. Serial No. 709,291.

ain and Ireland, and residing at Cardonald,

Glasgow. Scotland, have invented a certain new and useful Improvement 1n Safety- Valves, of which the following is a specification.

This invention relates to an improved construction of safety valves of the character set forth in our British Patent No. 16,038, dated July 9, 1909, and our U. S. Patent No. 1,026,734, dated May 21, 1912, and wherein the movement of the main valve. or valves is controlled through the intermediary of a pilot valve or valves each of which latter is adapted when the fluid reaches a predetermined pressure topermit such fluid to act on a piston operatively connected to the main valve or the correspondmg main valve, whereby the main valve or the corresponding main valve is opened.

The novelty of the invention consists in the combination of elements hereinafter particularly described and pointed out in the claim. I

In the accompanying drawings, Figure l is a part front elevation, part vertical section, Fig. 2 is a vertical section at right angles thereto, and Fig. 3 is a detail, of a safety valve of the double outlet type as constructed in accordance with the invention.

Referring to the drawings, the safety valve comprises a casing A provided with inlet and outlet branches B and C and having located within it the main valves D which are adapted to be controlled by spring-loaded pilot valves E each within a casing F communicating with the atmosphere by means of ports G and with the inlet branch B by means of a passage H, the spindle D of each of the valves D being secured to a piston I adapted to reciprocate within a cylinder J on the casing A. The chamber of each cylinder J is coaxial with a main valve E, and is disposed at one side of the casing A between the inlet and outlet branches thereof. The springs K for closing the pilot valves E are each located within an extension F of the casing F and extend between the upper end of said casing (see Fig. 3) and a flange L of a piston-like enlargement L of the respective pilot valve spindle, each of said pilot valves being operated manually, if desired, through the in termediary of a spindle L provided with a handle L Each of the main valves may also be operated independently by means of an arm D secured to a rock shaft D adapted to be actuated so as to cause said arm D to press on the end of the valve spindle D Each pilot valve E normally rests on a seat E and is provided with a hollow ex tension E which projects upwardly and receives a reduced portio-n L of the pistonlike enlargement L around which enlarge ment is formed an annular chamber Q and annular passage R, the chamber Q, being in constant communication with the atmosphere by means of the ports G. Freely surrounding the lower end of the pilot valve spindle is an axially movable flexible disk S or the like which rests normally on a seat T afforded by the upper end of the extension E clearance being provided at U between the disk S or the like and the face L of the piston-like enlargement D, the clearance at U determining the amount of lift of the disk S or the like and the face L serving as a backing for said disk or the like to prevent its being deflected into the chamber Q.

The action of the valves being the same in each case, the following description of the operation of one of the valves will suffice:-Fluid under pressure passes into the casing A through the inlet branch B and serves to keep the main valve D closed. The fluid also enters the passage H and exerts a pressure on the underside of the pilot valve E, and when the pressure he comes excessive the pilot valve is raised off,

its seat and permits the fluid to escape to an annular space M, the escaping fluid acting on the underside of the flange e of the pilot valve and. lifting it smartly from its seat E so that the face L of the enlargement L is moved upwardly relatively to a seat V disposed opposite the seat E whereupon fluid passes into the chamber W in the pilot valve casing F and causes the flexible disk S to engage with the face L and seat V so as to provide a fluid-tight joint with said seat V and prevent escape of fluid to the atmosphere by way of the annular chamber Q and the ports G, a fluid-tight joint being insured regardless of any wear orv grinding of the pilot valve or its seat.

The fluid then passes from the pilot valve casing F along a passage P to the cylinder Patented Mar. 18, 1913.

J and exerts pressure on the piston I,-which piston is of greater area than the valve D and on that accountis moved by the fiuid admitted to said cylinder until the outer face of the valve D comes in contact with a stopper or projection a. In this position the main valve is fully open and allows the fluid to escape through the outlet branch C. When the fluid pressure falls, the disk S is eased off the seat V by the action of the face L and fluid immediately escapes to the upper side of the pilot valve thereby assisting said valve to drop smartly on to its seat E and cutting off connnunication between the passage H and the port P leading to the cylinder J. Simultaneously, the fluid within the cylinder J escapes therefrom to the atmosphere by Way of the passage P, the annular chamber Q and the ports G, whereupon the main valve is closed due to the difference of pressure on the inlet and outlet sides of said valve and the pressure in the outlet branch C, and the difference in area between the main valve and the piston.

It will be understood that while we have shown the invention applied to a safety valve of the double outlet type it is equally applicable to a safety valve of the single outlet type.

Having now described our invention What we claim and desire to secure by Letters Patent of the United States is 1- In a safety valve, in combination, a casing provided with inlet and outlet branches and having a cylindrical chamber disposed at one side of said casing and between said branches, a main valve seated Within said casing and arranged coaxial with said chamber and having a valve stem, a piston fitted to said valve stem and adapted to reciprocate Within said cylindrical chamber, a second casing located exteriorly of the first mentioned casing and communicating with said cylindrical chamber, said second casing being provided with oppositely disposed seats, a spring-closed pilot valve adapted to engage one of said seats and serving to control. said main valve, said pilot valve having a hollow extension, a valve spindle having a piston-like enlargement or portion having a reduced part extending into said hollow extension of said pilot valve, :1 re cessed casing part affording an annular chamber surrounding said piston-like enlargement, and having ports to aiford outlets from said annular chamber, said casing part being also recessed to afford an annular passage from said annular chamber, and a flexible member which is separate from and thus movable axially relatively to said pilot valve so as to be adapted to close said annular passage, when desired.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

ROBERT COC'KBURN. DONALD MAGNICOLL.

Witnesses VVALLAcE CnANs'roN FAmwnATHnn, JOHN MCCLEARY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). G. 

